Laminar Multi-Layer Piezoelecric Roll Component

ABSTRACT

A multi-layer piezoelectric component includes a plurality of piezoelectric layers, a first inner electrode sheet, a second inner electrode sheet, a first outer electrode, and a second outer electrode. The piezoelectric layers are wound around an axis to form a laminar roll having first and second end faces transverse to the axis. The piezoelectric layers include at least one first layer and at least one second layer. Each of the first and second layers has opposite first and second edges respectively at the first and second end faces, and opposite inner and outer circumferential surfaces. The first and second inner electrode sheets respectively overlie the inner circumferential surfaces of the first and second layers. The first and second outer electrodes are respectively and electrically connected to the first and second inner electrode sheets.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a multi-layer piezoelectric component, moreparticularly to a multi-layer piezoelectric component having a laminarroll formed by winding a plurality of piezoelectric layers.

2. Description of the Related Art

Referring to FIGS. 1 and 2, a conventional laminar piezoelectriccomponent 1 is shown to include a plurality of piezoelectric ceramicsheets 11, a plurality of first inner electrode sheets 12, a pluralityof second inner electrode sheets 12′, a first outer electrode sheet 13,and a second outer electrode sheet 14. The first and second innerelectrode sheets 12,12′ are alternately sandwiched between two adjacentones of the piezoelectric ceramic sheets 11. The first outer electrodesheet 13 is overlaid on an uppermost one of the piezoelectric ceramicsheets 11, and is electrically connected to the first inner electrodesheets 12. The second outer electrode sheet 14 is underlaid beneath alowermost one of the piezoelectric ceramic sheets 11, and iselectrically connected to the second inner electrode sheets 12′.

The laminar piezoelectric component 1 can be used in applications, suchas a high voltage electric source for a television set, an ozonegenerator, and the like. Currently, the laminar piezoelectric component1 is also applicable to an electric source for a backlight module of aportable component. As compared to a conventional electromagnetictransformer, the conventional laminar piezoelectric component 1 hasadvantages, such as low power consumption, high transforming efficiency,low current leakage, reduced size, ease of integration with othercomponents, etc. However, in order to assure the electrical connectionof the outer electrode sheets 13,14 to the inner electrode sheets 12,12′in the aforesaid manner, a complicated laminating process is required,which in turn increases the manufacturing difficulty. Therefore, it isdesired to reduce cost by minimizing the volume of the laminarpiezoelectric component, and by simplifying the manufacturing processthereof.

SUMMARY OF THE INVENTION

Therefore, the object of the present invention is to provide amulti-layer piezoelectric component which has a laminar roll formed bywinding a plurality of piezoelectric layers so as to simplify themanufacturing process and to reduce the manufacturing cost.

A multi-layer piezoelectric component according to this inventionincludes a plurality of piezoelectric layers, a first inner electrodesheet, a second inner electrode sheet, a first outer electrode, and asecond outer electrode. The piezoelectric layers are wound around anaxis to form a laminar roll having first and second end faces transverseto the axis. The piezoelectric layers include at least one first layerand at least one second layer. Each of the first and second layers hasopposite first and second edges respectively at the first and second endfaces, and opposite inner and outer circumferential surfaces. The firstand second inner electrode sheets respectively overlie the innercircumferential surfaces of the first and second layers. The first andsecond outer electrodes are respectively and electrically connected tothe first and second inner electrode sheets.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features and advantages of the present invention will becomeapparent in the following detailed description of the preferredembodiments with reference to the accompanying drawings, of which:

FIG. 1 is a perspective view of a conventional laminar piezoelectriccomponent;

FIG. 2 is a sectional view of the conventional laminar piezoelectriccomponent;

FIG. 3 is an exploded perspective view of the first preferred embodimentof the multi-layer piezoelectric component according to this invention;

FIG. 4 is a fragmentary exploded perspective view of the first preferredembodiment;

FIG. 5 is a sectional view of the first preferred embodiment;

FIG. 6 is a perspective view showing the arrangement relationship amongpiezoelectric layers and inner electrode sheets of the first preferredembodiment;

FIG. 7 is an exploded perspective view of the second preferredembodiment of the multi-layer piezoelectric component according to thisinvention;

FIG. 8 is a sectional view of the second preferred embodiment;

FIG. 9 is a sectional view of the third preferred embodiment of themulti-layer piezoelectric component according to this invention;

FIGS. 10, 11, and 12 illustrate consecutive steps for producing thefirst preferred embodiment of the multi-layer piezoelectric componentaccording to this invention;

FIG. 13 is a sectional view of the fourth preferred embodiment of themulti-layer piezoelectric component according to this invention;

FIG. 14 is a sectional view of the fifth preferred embodiment of themulti-layer piezoelectric component according to this invention; and

FIG. 15 is a sectional view of the sixth preferred embodiment of themulti-layer piezoelectric component according to this invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Before the present invention is described in greater detail, it shouldbe noted that like elements are denoted by the same reference numeralsthroughout the disclosure.

Referring to FIGS. 3, 4, 5, and 6, the first preferred embodiment of themulti-layer piezoelectric component according to this invention is shownto include a central post 2 that extends along an axis (A), threepiezoelectric layers 31, two first inner electrode sheets 32, a secondinner electrode sheet 32′, a first outer electrode 4, and a second outerelectrode 5. The piezoelectric layers 31 are wound around the centralpost 2 to form a laminar roll 3 having first and second end faces301,302 transverse to the axis (A). The piezoelectric layers 31 includetwo first layers 31′ and one second layer 31″. The first and secondlayers 31′,31″ are disposed to alternate with each other. Each of thefirst and second layers 31′,31″ has opposite first and second edges313,314 respectively at the first and second end faces 301,302, andopposite inner and outer circumferential surfaces 311,312. The first andsecond inner electrode sheets 32,32′ respectively overlie the innercircumferential surfaces 311 of the first and second layers 31′,31″. Thefirst and second outer electrodes 4,5 are respectively and electricallyconnected to the first and second inner electrode sheets 32,32′.

Specifically referring to FIG. 5, the first inner electrode sheet 32 hasa first end 321 flush with the first edge 313 of the first layer 31′,and a second end 322 which is opposite to the first end 321 and which isspaced apart from the second edge 314 of the first layer 31′. The firstouter electrode 4 is mounted on the first end face 301 of the laminarroll 3 and is in contact with the first end 321 of the first innerelectrode sheet 32. The second inner electrode sheet 32′ has a third end321′ flush with the second edge 314 of the second layer 31″, and afourth end 322′ which is opposite to the third end 321′ and which isspaced apart from the first edge 313 of the second layer 31″. The secondouter electrode 5 is mounted on the second end face 302 of the laminarroll 3 and is in contact with the third end 321′ of the second innerelectrode sheet 32′.

While the laminar roll 3 is shown to have a circular cross section inthe preferred embodiment, the laminar roll 3 can also be formed to havea cross section with other suitable shapes, such as a polygon.

Referring to FIGS. 7 and 8, the second preferred embodiment of thisinvention is shown to be substantially similar to the first preferredembodiment except that the length of each inner electrode sheet 32 isnot identical to that of the adjacent piezoelectric layer 31. Therefore,the areas (indicated by the dotted oval lines in FIG. 8) of the laminarroll 3 proximate to and distal from the central post 2, respectively,are devoid of the inner electrode sheets 32.

Referring to FIG. 9, the third preferred embodiment of this invention isshown to be substantially similar to the first preferred embodimentexcept that the laminar roll 3 is composed of two piezoelectric layersand two inner electrode sheets laminated alternately to each other.

Referring to FIGS. 10, 11, and 12, during the manufacture of themulti-layer piezoelectric component of this invention, a plurality ofceramic sheets 31′″ made of a material, such as lead-zirconate-titanate,barium titanate and the like, are initially prepared. A plurality ofinner electrode sheets 32″ are then printed on the ceramic sheets 31′″.The inner electrode sheets 32″ are made of conductive metal, such asnickel, copper, zinc, and mixtures thereof.

The ceramic sheets 31′″ printed with the inner electrode sheets 32″ arewound subsequently around the central post 2 using a winding apparatus6. The central post 2 is preferably made of a material such aslead-zirconate-titanate, barium titanate and the like. The windingapparatus 6 includes three tension bars 61, two rollers 62, and onepress axle 63. The tension bars 61 permit extension of the ceramicsheets 31′″ in a tensed state. The press axle 63 prevents loosening ofthe ceramic sheets 31′″ after being wound around the central post 2.

After winding the ceramic sheets 31′″ to result in a wound body 3′, thewound body 3′ is cut along cutting lines (X) to obtain a plurality ofgreen ceramic rolls, which are then sintered at elevated temperatures toobtain the laminar rolls 3.

Finally, the first and second outer electrodes 4,5 are mounted on thefirst and second end faces 301,302 of each of the laminar rolls 3 tocomplete the multi-layer piezoelectric component. Preferably, the firstand second outer electrodes 4, 5 are independently made of a materialsuch as nickel, copper, zinc, and mixtures thereof.

Referring to FIG. 13, the fourth preferred embodiment of this inventionis shown to be substantially similar to the first preferred embodimentexcept that the central post 2 for winding the ceramic sheets 31′″ ismade of a material that is capable of vaporizing at elevatedtemperatures. Therefore, the central post 2 is vaporized duringsintering so as to form the laminar roll 3 with a hollow center.

Referring to FIG. 14, the fifth preferred embodiment of this inventionis shown to be substantially similar to the first preferred embodiment,except for the following. The piezoelectric layers 31 include one firstlayer 31′ and one second layer 31″. The second inner electrode sheet 31′has a fifth end 323′ which extends axially and which interconnects thethird and fourth ends 321′,322′ of the second inner electrode sheet 31′.The fifth end 323′ of the second inner electrode sheet 31′ is exposedfrom the outer circumferential surface 312 of the second layer 31″. Thefirst outer electrode 4 is disposed over the outer circumferentialsurface 312 of the second layer 31″ and is in contact with the fifth end323′ of the second inner electrode sheet 32′.

Referring to FIG. 15, the sixth preferred embodiment of this inventionis shown to be similar to the fifth preferred embodiment except that thecentral post 2 is made of a material capable of vaporizing at elevatedtemperatures. Therefore, the central post 2 is vaporized duringsintering so as to form the laminar roll 3 with a hollow center.

In view of the aforesaid, the multi-layer piezoelectric componentaccording to this invention increases the electrode area therein, andenhances the output efficiency as well in view of the laminar rolltherein. The overall size of the multi-layer piezoelectric component ofthis invention is also reduced as compared to that of the prior art.Furthermore, in order to permit winding around the central post 2, thepiezoelectric layers 31 are relatively thin. Therefore, the multi-layerpiezoelectric component according to this invention can achieve anoutput efficiency identical or substantially identical to that of theprior art by using a relatively low current. Additionally, themulti-layer piezoelectric component of this invention can be producedthrough a relatively simple process.

While the present invention has been described in connection with whatis considered the most practical and preferred embodiments, it isunderstood that this invention is not limited to the disclosedembodiments but is intended to cover various arrangements includedwithin the spirit and scope of the broadest interpretation so as toencompass all such modifications and equivalent arrangements.

1. (canceled)
 2. A multi-layer piezoelectric component, comprising: aplurality of piezoelectric layers which are wound around an axis to forma laminar roll having first and second end faces transverse to saidaxis, said piezoelectric layers including at least one first layer andat least one second layer, each of said first and second layers havingopposite first and second edges respectively at said first and secondend faces, and opposite inner and outer circumferential surfaces; afirst inner electrode sheet and a second inner electrode sheetrespectively overlying said inner circumferential surfaces of said firstand second layers; and first and second outer electrodes respectivelyand electrically connected to said first and second inner electrodesheets, wherein said first inner electrode sheet has a first end flushwith said first edge of said first layer and a second end which isopposite to said first end, said first outer electrode being mounted onsaid first end face of said laminar roll and being in contact with saidfirst end of said first inner electrode sheet.
 3. The multi-layerpiezoelectric component as claimed in claim 2, wherein said second endof said first inner electrode sheet is spaced apart from said secondedge of said first layer, said second inner electrode sheet having athird end flush with said second edge of said second layer, and a fourthend which is opposite to said third end and which is spaced apart fromsaid first edge of said second layer, said second outer electrode beingmounted on said second end face of said laminar roll and being incontact with said third end of said second inner electrode sheet.
 4. Themulti-layer piezoelectric component as claimed in claim 3, wherein thenumber of said piezoelectric layer is more than two, said first andsecond layers being disposed to alternate with each other.
 5. (canceled)6. The multi-layer piezoelectric component as claimed in Claim 2,wherein said piezoelectric layers are made of lead-zirconate-titanate.7. A multi-layer piezoelectric component, comprising: a plurality ofpiezoelectric layers which are wound around an axis to form a laminarroll having first and second end faces transverse to said axis, saidpiezoelectric layers including at least one first layer and at least onesecond layer, each of said first and second layers having opposite firstand second edges respectively at said first and second end faces. andopposite inner and outer circumferential surfaces, a first innerelectrode sheet and a second inner electrode sheet respectivelyoverlying said inner circumferential surfaces of said first and secondlayers. first and second outer electrodes respectively and electricallyconnected to said first and second inner electrode sheets, and a centralpost that extends along said axis, said laminar roll being wound aroundsaid central post, wherein said central post is made of a materialselected from a group consisting of lead-zirconate-titanate and bariumtitanate.
 8. A multi-layer piezoelectric component, comprising: aplurality of piezoelectric layers which are wound around an axis to forma laminar roll having first and second end faces transverse to saidaxis, said piezoelectric layers including at least one first layer andat least one second layer, each of said first and second layers havingopposite first and second edges respectively at said first and secondend faces, and opposite inner and outer circumferential surfaces, afirst inner electrode sheet and a second inner electrode sheetrespectively overlying said inner circumferential surfaces of said firstand second layers, first and second outer electrodes respectively andelectrically connected to said first and second inner electrode sheets,and a central post that extends along said axis, said laminar roll beingwound around said central post wherein said central post is made of amaterial capable of vaporizing at elevated temperatures.
 9. Themulti-layer piezoelectric component as claimed in Claim 2, wherein saidpiezoelectric layers are made of barium titanate.
 10. (canceled)
 11. Themulti-layer piezoelectric component as claimed in Claim 2, wherein saidfirst and second inner electrode sheets are made of a material selectedfrom the group consisting of nickel, copper, and zinc.
 12. Themulti-layer piezoelectric component as claimed in Claim 2, wherein saidfirst and second outer electrode sheets are independently made of amaterial selected from the group consisting of nickel, copper, and zinc.13. The multi-layer piezoelectric component as claimed in Claim 2,wherein said laminar roll has a cross section with a shape selected fromthe group consisting of a circle and a polygon.
 14. The multi-layerpiezoelectric component as claimed in claim 2, wherein said second innerelectrode sheet has a third end flush with said second edge of saidsecond layer, and a fourth end which is opposite to said third end andwhich is spaced apart from said first edge of said second layer, saidsecond inner electrode sheet further having a fifth end which extendsaxially and which interconnects said third and fourth ends, said fifthend being exposed from said outer circumferential surface of said secondlayer, said first outer electrode being disposed over said outercircumferential surface of said second layer and being in contact withsaid fifth end of said second inner electrode sheet.
 15. The multi-layerpiezoelectric component as claimed in claim 14, wherein saidpiezoelectric layers include one said first layer and one said secondlayer.